Immune system follows circadian clock

Mice with jet lag have boosted supply of cells linked to inflammation

UPSET CLOCK Disrupting a mouse’s internal clock boosts the abundance of one type of immune cell, TH17 (false-colored green), in the lining of the intestines (gray fingerlike projections). The extra immune cells may make animals prone to inflammatory diseases.

Jet lag goofs up more than just sleep schedules: Tinkering with the body's clock confuses the immune system too.

In mice, a type of immune cell linked to inflammation depends on daily cycles of light and dark, researchers report in the Nov. 8 Science. The finding could help explain the connection between inflammatory diseases and chronic clock disruptions, such as those experienced by frequent fliers and night shift workers.

“This has implications for all of us,” says study author Lora Hooper, an immunologist at the University of Texas Southwestern Medical Center in Dallas. “None of us go to sleep when the sun sets or get up when the sun rises.” Soaking up artificial light when it’s dark outside might predispose people to immune disorders such as inflammatory bowel disease, multiple sclerosis and rheumatoid arthritis, she says.

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